1. Field of the Invention
The present invention relates generally to the field of turbine blade design and fabrication and, more specifically, to an improved side-entry integral shroud blade.
2. Description of the Related Art
A typical side-entry rotary turbine blade has a root portion, a platform portion, and an airfoil portion. For shrouded blades, the tip of the airfoil portion is connected to a shroud through a tenon, or the shroud may be integrally formed at the tip.
A conventional, integral shroud blade is illustrated in FIG. 1 and is generally referred to by the numeral 10. The blade 10 has a root portion 12, a platform portion 14, an airfoil portion 16 including a leading edge 18 and a trailing edge 20, and an integral shroud 22. Conventionally, the shroud 22 is substantially rectangular and functions as a rotating seal and improves blade vibratory characteristics due to shroud snubbing. As is illustrated in FIG. 1, a shroud lightening groove 24 is formed to place the center of gravity above the centroid of the root portion, thus minimizing eccentric stresses introduced during blade rotation. The shroud 22 is also centered in the tangential direction.
Control of the shroud center of gravity in the tangential direction has been difficult with the design illustrated in FIG. 1, incorporating a lightening groove.